Multiple fights in an Auckland suburb might be behind findings of blood rather than from a single wounded person, police believe.

They have arrested a 17-year-old and charged him with assault over the incident in Beach Haven.

Earlier today Detective Senior Sergeant Brett Batty of Waitemata police said a quantity of blood was first discovered on the Beach Haven wharf about 3.30am. Another blood find, 400 metres away from the wharf, was discovered soon afterwards on a footpath near Rangatira Road. Now police say that have confirmed that a fight took place between a number of people on the Beach Haven wharf.

Enquiries throughout the day have involved speaking with neighbours in the area, a thorough scene examination, and the review of CCTV footage. The 17-year-old will appear in the North Shore District Court later this week.

"We're still working to determine exactly what took place in the early hours of this morning, however from what we know now we believe it's quite possible that the blood is the result of a number of fights between several parties, and that the blood may not necessarily be from the same person," Batty said.

Police have checked with the hospitals and it appears that no-one has presented themselves with injuries that are consistent with a fight.

They say after an extensive search they are satisfied that no-one is lying there in an injured state.Anyone who has information on this morning's incident is still encouraged to call the North Shore Police on 09 477 5000.